The artistic conception expressed in the poem, such as "The sunrise makes the river red, and the spring makes the river blue", "Two orioles sing green willows, a row of egrets rise to the sky" and "The sun is tempered by pine trees, and the sky is green and wet", are the special functions and aesthetic characteristics of the author's color vision, which makes the poem better express the author's thoughts and feelings.
In visual arts, color, as the first visual impression, has far-reaching artistic charm and often has the power of sound. When people observe an object, the visual nerve reflects the color the fastest, followed by the shape, and finally the texture and details of the surface. Therefore, in practical art, there is often a saying that "the color is far away and the flower is near, and the color is seen first, and the flower is divided into seven parts". It vividly illustrates the importance of color in art design.
"The feeling of color.
The transmission ways of human color sense information are light source, color object, eyes and brain, which are the four major elements of human color sense formation. These four elements not only make people feel the color, but also are the conditions for people to judge the color correctly.
The radiant energy of light source and the reflection of objects belong to the category of physics, and the brain and eyes are the contents of physiological research, but the color is always based on physics, and the feeling of color always contains the reflection of the psychological and physiological functions of color, which makes people produce a series of comparisons and associations.
The Chromaticity Committee of the American Optical Society once defined color as a characteristic of light except the temporal and spatial inhomogeneity, that is, the radiation of light can stimulate the retina and make the observer obtain the scene through vision.
In China's national standard GB5698-85, the definition of color is: color is a visual characteristic other than image produced by light acting on human eyes. According to this definition, color is the visual characteristic of physical stimulation acting on people's eyes, and people's visual characteristics are dominated by the brain, which is also a psychological reflection.
In the process of human understanding and transforming the objective world, the colors of natural scenery gradually have a certain psychological impact on people, resulting in cold and warm, soft and hard, distance and weight, and various associations generated by colors. For example, from red to flame, blue to the sea, this association has produced a clear concept, which makes people feel different about different colors.
Chapter II Physical Theory of Color
"The relationship between color and light.
Without light, there is no color. Light is a necessary condition for people to perceive color, and color comes from light. Therefore, light is the source of color, and color is the expression of light.
"the essence of light
Newton's particle theory, Huygens' elastic wave theory, Maxwell's electromagnetic theory, Einstein's light quantum theory and modern wave-particle duality theory.
Visible light-In the range of electromagnetic wave radiation, only radiation with the wavelength of 380nm to 780nm( 1nm= 10-9mm) can cause people's visual sense, and this light wave is called visible light.
"The dispersion experiment of light.
Traditionally, this color band is called spectrum.
"Seven-color theory of spectrum"
In ancient Greece, Aristotle believed that the brilliant colors of everything in the world were composed of seven basic colors. The seven basic colors are white, yellow, red, purple, green, cyan and black. Although he doesn't have much basis, the number "seven" has ruled the European scientific community for two thousand years.
There is no evidence to prove whether Newton was also influenced by this, but he became a devout believer in his later years. At that time, the music dedicated to God by the English Church adopted a seven-tone scale with D as the main tone, so the seven colors of the spectrum were divided into red, orange, yellow, green, cyan, blue and purple.
"Color light additive mixture (additive mixture)
-& gt； Determination of three primary colors of color and light
There are three basic colors in colored light. Their colors are red, green and blue. These three kinds of colored light are not only the main colored light obtained by white light decomposition, but also the main components of mixed colored light, which can match the spectral response interval of human retinal cells and conform to the visual physiological effect of human eyes. These three colors are mixed in different proportions, and almost all colors in nature can be obtained, and the mixed color gamut is the largest; Moreover, these three colors are independent, and one primary color cannot be mixed with other primary colors. Therefore, we call red, green and blue the three primary colors of color light.
In order to unify the understanding, CIE stipulated in 193 1 that the wavelengths of three primary colors are λ r = 700.0 nm, λ g = 546. 1 nm and λ b = 435.8 nm.
When two or two colors of light are mixed, it will stimulate people's visual organs at the same time or continuously in a very short time, resulting in a new color feeling. We call this color light mixing additive color mixing. This method of mixing more than two colors to present another color light is called color light additive method.
The color matching experiment conducted by CIE shows that neutral white light can be matched when the brightness ratio of red, green and blue is1.0000: 4.5907: 0.0601,and its expression is (R)+(G)+(B)=(W).
R, g and b are three primary colors.
C, m and y are the secondary colors of color and light.
W is the third color of colored light (the same is true of colored light obtained by unequal mixing of three primary colors)
"additive mixed species
-& gt； Additive mixing outside the visual organ
Additive mixing outside the visual organ means that colored light has been mixed into new colored light before entering the human eye. The stimulation of each primary color light in mixed color light to human eyes starts at the same time, which is the simultaneous mixing of color light.
-& gt； Additive mixing in visual organs
Additive color mixing in visual organs means that monochromatic light participating in mixing stimulates three color-sensitive cells of human eyes respectively, which makes people produce a new comprehensive color feeling, including static mixing and dynamic mixing.
"additive mixing in visual organs
-& gt； Static mixing
Static mixing refers to the mixing of various colors when reflected light stimulates human eyes at the same time. For example, the juxtaposition of fine color points, the mixed color formed by interlaced monochromatic thin lines is static mixed color, and the reflected light of various colors stimulates the human eye at the same time, which is also the mixed color of color and light.
Due to the limitation of visual acuity, people can't distinguish color points or lines that are too close together and have a small area, but regard them as a mixed color.
-& gt； Dynamic mixing
Dynamic mixing refers to the mixing of reflected color light by human eyes when various colors are dynamic, such as when the color wheel rotates rapidly. The reflected light of various color blocks will not appear in human eyes at the same time, but one color light disappears and the other color light appears, which stimulates the color sensitive cells of human eyes alternately. Because of the persistence of human vision, people's perception of color is mixed.
"the law of color and light mixing
-& gt； Continuous variation law of color and light
If the red light remains unchanged, change the intensity of green light to make it gradually weaken, and you can see various mixed colors from yellow to red.
-& gt； Complementary color law
There are three basic complementary colors: red-cyan, green-magenta and blue-yellow.
Light of one color is absorbed when it shines on an object together with its complementary color. If blue light shines on a yellow object, it appears black.
-& gt； Intermediate color law
Any two non-complementary colors are mixed to produce an intermediate color. Its color depends on the relative energy of two colors, and its brightness depends on their distance in tone order.
-& gt； Substitution law
Light with the same color and appearance has the same effect in color and light mixing, regardless of whether their spectral components are the same or not. All visually identical colors are equivalent. That is, similar colors are still similar after mixing.
If the color light A=B and C=D, then: a+c = b+d.
-& gt； Brightness addition law
The total brightness of a mixed color composed of several colors is equal to the sum of the brightness of various colors that make up the mixed color.
"subtractive blending"
Pigment: Granular substance with the purest color sense, which has an ideal diffuse reflection state and is the most ideal inherent color.
The three primary colors of pigment are cyan, magenta and yellow.
Color is the inherent optical characteristic of the chemical structure of an object. All objects are colored by objective light reflection. The so-called "subtractive color" means that adding a primary color pigment will subtract a primary color light (complementary color light) from the incident light. Therefore, when pigments are mixed, one or more monochromatic lights are subtracted from polychromatic lights to present another color, which is called subtractive color method.
"subtractive blending"
Pigment coloring is due to the selective absorption of complementary color components in incident light and the reflection or transmission of remaining colored light to human eyes. The essence of subtractive method is the selective absorption of a monochromatic light in polychromatic light by pigments, which weakens the energy of incident light. Due to the decrease of color light energy, the brightness of mixed colors decreases.
Supplementary pigment
Black can be obtained by mixing three pigments in equal proportions, namely:
(Y)+(M)+(C)=(Bk). If yellow and magenta are first mixed to get the middle red, and then mixed with cyan, the above formula can be written as follows:
(R)+(C)=(Bk).
In this way, when two pigments are mixed into black, we call them complementary colors, and these two colors are called complementary colors. Among pigments, magenta and green, yellow and blue are also a pair of complementary colors.
"The relationship between addition and subtraction.
Additive method and subtractive method are aimed at colored light, additive method refers to the addition of colored light, and subtractive method refers to the weakening of colored light. Additive method is a method of color matching with light. Subtraction is a method of mixing pigments to produce color.
Additive method is a color effect produced by two or more colored lights simultaneously stimulating human optic nerve; Subtraction method refers to subtracting a part of colored light from white light or other polychromatic light to produce a color effect stimulated by another colored light.
From the complementary relationship, there are three pairs of complementary colors: R-C; g-M； B-Y. In the color light additive method, complementary colors are added to obtain white; In the pigment subtractive method, complementary colors are added to obtain black.
Chapter III Theory of Color Physiology
-& gt； Visual channel
The human eye is like a beautiful camera. More specifically, it is a video camera. The human visual system has eyes stimulated by light->; Perform conversion-> transmission to brain-> color formation processing of the whole visual channel.
The visual channel is as shown in the figure. It starts from the eyeball and accepts information from the outside world->; Will through the nervous system into bioelectricity information->; Left and right lateral geniculate bodies. In transmission, the information from the nasal side of retina crosses left and right. After passing through the left and right lateral geniculate bodies, their respective information is transmitted to the striatum area of the occipital cortex of the left and right hemispheres, the end point of the visual channel. Visual information is finally processed into visual perception, including color perception.
-& gt； eyeball
The window of eyeball receiving visual information has the structure as shown in the figure.
Overall structure->; Black box,
Eye convergence->; shutter
The transparent cornea is surrounded by opaque conjunctiva.
Behind the cornea is an anterior chamber filled with transparent aqueous liquid.
Behind it is an opaque iris.
The round hole in the middle of the iris is called the pupil.
Crystal body->; Biological convex lens with variable curvature focusing.
Vitreous body of posterior chamber->; Imaging on the retina of the inner wall of eyeball->; Form a correct inverted image of the whole field of vision.
The curved surface of the retina improves the surrounding focusing problem, so the field of vision is very large.
Eyeball-> Precision optical system with a diameter of about 25 mm
There are two axes on the eyeball, one is the optical axis, and the other is the visual axis of the line of sight when observing. The fovea at the intersection of retina and visual axis is called fovea. As a photoreceptor, retina is consistent with the variable resolution structure of cerebral cortex, and it also has a very ingenious variable resolution structure. The fovea has a high resolution, which is the central visual area. When leaving the central fossa, the resolution drops rapidly, and the farther away it is, the lower it is. When observing, the visual axis always faces the details of the observed object, and it is imaged in the central fossa with the highest resolution. Not far from the nasal side of the optic axis, there is a convergence of the optic nerve, called the optic papilla. The optic nerve leads the eyeball from here, forming a blind spot on the retina. But the blind spot is not a black hole that forms vision, where the vision is full of information obtained by the surrounding photoreceptor cells, so it is dizzy with the surrounding area and difficult to be detected.
-& gt； photoreceptor
There are two kinds of photoreceptor cells in retina that are sensitive to electromagnetic waves in visible light band: one is cylindrical photoreceptor cells, also known as columnar cells; One is cone-shaped photosensitive element, also known as cone-shaped battery. Cylinders have extremely high light sensitivity and can distinguish extremely weak light changes at low light level.
The sensitivity of a cone is much lower than that of a cylinder. Under the dim light level, it is completely in the cut-off state and cannot work normally. R cone with the highest sensitivity in long wave band; G cone has the highest sensitivity in the middle band; B-cone with the highest sensitivity in short-wave band.
Cylindrical cells can only feel the brightness difference, and the resolution of subtle levels of objects is poor;
Cone cells can feel the color of objects and distinguish the subtle levels of objects.
-& gt； Dark vision, bright vision and intermediate vision
The visual state of a cylinder in a dark environment is called dark vision.
Because there are no pillars in the central fossa, the vision there is full of information about the surrounding pillars. In other words, the vision at night is hazy, and it is impossible to observe the details of objects in detail.
During the day, columnar cells are saturated and lose their ability to work. All visual phenomena depend entirely on the role of the cone, that is, clear vision. According to the distribution characteristics of the visual cone, its resolution is the highest at the central fossa, so when people observe, they always have the reflection activity of turning the visual axis to the object, so that the observed details can be imaged at the central fossa. Reading activity is the most typical example.
Due to the characteristics of visual state, when the light level is between two states, there will be an indirect visual state. When the environment changes from dark to bright, people's vision changes from dark to bright. Blue is not only the first color that color vision comes back, but also the last color vision that disappears when the environment is getting dark.
-& gt； Visual field color sensitive area
True vision depends on the clear vision established by the cone. This is not only reflected in the subtle observation, but also in the fact that color phenomenon has become the main visual phenomenon of human beings. Because of the distribution characteristics of the cone, the inconsistency of color perception in the field of vision is determined.
Outside-> inside
Completely colorless sensory area (black and white perception, motion sensitivity)->; Blue-yellow area (without complete color vision)-> Red and green areas (forming a complete color vision).
-& gt； Young-Helmholtz trichromatic vision theory
Is the wavelength a color?
180 1 year, British scientist Thomas T. Young founded the three-component theory of color vision.
There are three kinds of particles that can resonate with red, green and blue wavelengths at all positions in the retina. When they are illuminated, they will resonate according to their own inherent resonance curve, and transmit their vibration values to the brain center through three kinds of nerve fibers to form color vision.
In 1950s and 1960s, German physicist H. Helmholtz developed Yang's trichromatic theory of color vision and proposed a trichromatic model with parallel structure, as shown in Figure 4. He believes that there are three different types of cells in the retina, which are stimulated by light, and respectively convert this excitement value into the special energy inherent in their respective optic nerves and send it to the brain, where they form a red feeling, a green feeling and a blue feeling, and finally merge into a complete color vision. These three types of cells and nerves are called red cells, green cells, blue cells and red nerves, green nerves and blue nerves respectively. They form three groups of color vision channels with parallel structures respectively. Since then, this theory has been called Yang Yi-Helmholtz color vision trichromatic theory.
Success: Yang Yi Helmholtz's tricolor theory of color vision successfully explained Newton's famous saying that "light has no color". He also explained how humans received colorless light stimuli and merged a strange and colorful world in their brains. Therefore, people can understand why color feeling is more subjective than any other feeling, and better explain the principle of three-color mixing.
Disadvantages: the mechanism of color psychological phenomenon cannot be explained.
1. Why is there always a so-called complementary color with opposite personality in any color mixed by three colors?
2. Why does the juxtaposition of complementary colors greatly strengthen their opposing personalities? Why do their mixing cancel each other out, even turning into black, white and gray in light color?
3. Why can we observe blue red or yellow red, but not green red?
4. Why are the ends of the spectrum not connected, but the color sense can be arranged in a color ring connected end to end?
-& gt； Hailing's Theory of Opposing Colors
1870, German physiologist Hering (E. Hering, 1834- 19 18) put forward the theory of color vision antagonistic to color vision, and put aside preconceived prejudice, thought that human color vision was the fusion of three groups of opposite basic color vision-antagonistic colors in the brain. In his view, its material basis is that there are three different types of cells in the visual channel, which have black and white, red, green and blue yellow visual substances respectively. Stimulated by light, these visual substances have different degrees of biochemical reactions of synthesis or decomposition, thus showing different values of positive or negative potentials. It is these potentials that form the basic color sense of black or white, red or green, blue or yellow respectively. Finally, a basic color sense among the three opposing colors is integrated into a comprehensive color sense in the brain, which is Hailing's theory of opposing colors.
-& gt； Modern color vision stage theory
Adam model proposed by 1923 is the prototype of modern color vision model. After improvement, it is the theoretical model of modern color vision stage as shown in the figure.
In this model, there are two independent systems, namely, the bright system and the dark system. Dark vision is a Purkinje system composed only of columnar cells. But it is more complicated. It has a light receiving terminal consisting of three cones, R, G and B, distributed on the retina, which supports Helmholtz's trichromatic theory. Later, among the responses obtained from the three cones of R, G and B, the response of R and B synthesized herring red R signal, the response of B and G synthesized herring yellow Y signal, and only the response of B directly became herring blue signal. The combination of the four signals corresponds to the psychological pure color. Antagonistic colors (Y-B) and (R-G) form a subtraction circuit, and each signal is mixed into a black-and-white signal W. At this later stage, three groups of antagonistic colors are formed to support Herring's theory. Finally, three groups of opposing colors merge into a realistic color vision in the brain. Three sets of opposing colors are transmitted in the visual channel.
Chapter IV Color of Objects and Color of Light Sources
-& gt； Objects are colored.
Objects can be divided into two categories: luminous and non-luminous Among them, the non-luminous body is divided into transparent body and transparent body. Non-luminous objects can be divided into colorless objects and colored objects according to their absorption spectral characteristics.
-& gt； Colorless objects are colored.
Objects can absorb light with different wavelengths in the spectrum in equal ratio to different degrees, which is called non-selective absorption or equal ratio absorption and uniform absorption. Due to the different absorption rate, objects will appear a series of neutral colors from white, various grays to black in the sun, which is called achromatic. An achromatic object is called achromatic object.
-& gt； Colored objects are colored.
Most objects in nature have different absorption of light with different wavelengths. Some wavelengths absorb more while others absorb less. This absorption is called selective absorption. After selective absorption, the brightness of reflected or transmitted light decreases and the spectral components also change. Under white light, the reflected light or transmitted light of these selectively absorbed objects no longer stimulates the three color-sensitive cells of human eyes equally, giving people a sense of color.
-& gt； Object color
Because everything has the characteristic of selectively absorbing the light projected on its surface and reflecting the rest light, it is this reflected light that forms the color of the object in vision, which is called the object color.
Different substances have different selectivity, so they have different spectral absorption distribution characteristics and form different object colors.
A substance has an inherent spectral reflectivity distribution, so the spectral energy distribution of the reflected light of a specific object under white light irradiation is certain, and the color it presents is also certain. This color is called the inherent color of an object.
Some special substances also have surface colors, such as neon and rainbow in the sky after rain, and diamonds are caused by light refraction; Looking at the light source through feathers, silk patterns and scarves, we can see color stripes, which are caused by the diffraction of light. In addition, the interference of light can make the film with uneven thickness produce color under white light, such as soap bubbles and oil layers on the water surface.
-& gt； Factors affecting the color of objects
The color shown by the nature of the object itself is often called the intrinsic color of the object. However, the color of an object under different light sources, or different illumination angles, different observers, different object distances and different environments will all affect the inherent color of the object.
-& gt； Influence of light source color
Objects only have fixed optical characteristics such as absorption and reflection for different light waves, but there is no fixed color. The color of the object changes with the spectral composition of the light source. The inherent color of an object actually refers to the color of the object in the sun.
-& gt； Influence of Environmental Colors on Objects
-& gt； Influence of light source color
The color of the colored light projected on the object has the following two laws:
When (1) color light is projected on an achromatic object, the object produces non-selective absorption and reflection, and the color of the object is the same as that of the light source. When more than two colors of light are irradiated at the same time, an additive effect is produced. If blue light and green light illuminate a white object at the same time, cyan will appear.
(2) When a colored object is irradiated by colored light, the object produces fixed selective absorption and reflection, resulting in hypochromic effect. For example, a yellow object looks red in magenta light, green in cyan light and gray or black in blue light. It can be seen that objects reflect red light and green light and absorb blue light under different color light sources. The colored light reflected and absorbed by colored objects under different light sources is fixed. As long as the light source contains light that the object should reflect, the object will reflect, and if it contains light that should be absorbed, the object will absorb.
Sunlight is the main light source, but it is also changing. The composition of the solar spectrum varies with the relative position of solar irradiation (such as early, middle and late). In addition, with the change of season and weather, the sunshine is different. Observing the color of an object in different sunlight will change the color of the object.
-& gt； Influence of Environmental Colors on Objects
Under the irradiation of colored light source, the object is still dyed by the color of the light source to a considerable extent, which is called the color rendering of the light source.
The dyed color is called ambient color. The influence of environment on the color of objects has the following laws:
(1) The light receiving surface of an object is greatly influenced by the color of the light source, and its hue is a combination of the inherent color and the color of the light source, and its hue is cold.
(2) The color of the backlight surface of the object changes with the change of the environmental color, and its hue is a combination of the inherent color and the environmental color, and the hue is warmer.
(3) Due to the different angles of light sources, the object itself has different color changes. Hue is the combination of light source color, intrinsic color and environmental color, mainly due to the influence of intrinsic color.
-& gt； The color of an object is also influenced by its surface processing characteristics.
The surface of the object polished to an ideal mirror almost reflects the light emitted by the light source 100%, so the object almost loses its inherent color; Only the surface with complete diffuse reflection can truly show the inherent optical characteristics of matter and present the inherent color. As for the surface of general objects, it is always between these two extremes. In the highlight part, there are more specular reflection components and more light source colors. The gray part in the middle can better reflect the inherent color of the object.
Due to the adaptability of perception, the deviation of the same color in the whole field of vision will be neutralized, which leads to the constancy of visual perception, making this deviation difficult to find and almost still the inherent color of human perception. On the contrary, to understand the true nature of objects, we need to break through this psychological barrier with the help of reason. This is an important reason why the inherent color painting has occupied the western painting world for hundreds of years, and the impressionist painting came to the world about 200 years after Newton published the optical research results.
-& gt； Light source and light source color
The color of the light source is mainly determined by the energy distribution of the spectrum it emits, that is, the spectral power distribution of the light source. Spectral power distribution can be expressed by color temperature, which directly affects the color of light.
-& gt； Spectral distribution of light source
1. continuous spectrum
2. Linear spectrum
3. Mixed spectrum
-& gt； continuum
The light source emits a continuous spectrum with different intensities throughout the visible spectrum. That is, a continuous color band including various colors of light from red to blue is called a continuous spectrum. It can be produced by solid, liquid or high-pressure gas that emits light at high temperature. For example, carbon arc lamps emit carbon particles, and the temperature is as high as 4000℃; Incandescent tungsten filament emits light, and the filament temperature can reach 2000℃. Molten steel glows and gas glows, which means that liquid and gas glow at high temperature respectively.
-& gt； Linear spectrum
The hot vapor of an element can produce spectral lines with a certain wavelength, such as low-pressure mercury lamp and low-pressure sodium lamp, and only emit a narrow spectrum with a certain wavelength in the whole spectral region. This spectrum is called linear spectrum.
-& gt； Mixed spectrum
The spectra of some new electric light sources, such as xenon lamp and indium lamp, are arc discharge lamps with high air pressure in the tube, and the spectral components emitted by them are often very complex, including continuous spectral components and several prominent spectral lines. Such a light source spectrum is called a mixed spectrum. In addition to the above, there are dense line spectra that belong to linear spectrum but are closely arranged.